Top Democrats called on President Trump to cancel his summit next week with Russian leader Vladimir Putin, saying it’s the most immediate way to punish Moscow after Friday’s indictment of a dozen Russian military officers accused of interfering in the 2016 election.

Still other Democrats — and some Republicans — said the summit should go on, but Mr. Trump must firmly confront Mr. Putin over the interference, which was laid out in extraordinary detail in the indictment.

Russian military intelligence officers used phishing and malware attacks to steal emails of Hillary Clinton’s campaign chairman and other campaign officials and the Democratic National Committee, then released them to dent her campaign, prosecutors charged in the indictment, handed up by a federal grand jury in D.C.

“President Trump should cancel his meeting with Vladimir Putin until Russia takes demonstrable and transparent steps to prove that they won’t interfere in future elections,” said Senate Minority Leader Charles E. Schumer. “Glad-handing with Vladimir Putin on the heels of these indictments would be an insult to our democracy.”

Sen. Elizabeth Warren, Massachusetts Democrat, was more pointed: “Cancel your ridiculous Putin summit and get your butt on a plane back to the United States,” she said on Twitter.

Mr. Putin and Mr. Trump are slated to meet one-on-one Monday in Helsinki.

Mr. Trump has been less than clear on his beliefs about Russian efforts in the 2016 election. At times he has said he accepts his own government’s finding that Russians interfered, but other times has said he credits Mr. Putin’s insistence that Russia was innocent.

Investigators say they are able to cite which specific intelligence officers used which computers at which times to steal emails. They also then trace the emails as they were injected into the political campaign, serving to dent Mrs. Clinton in the final months before the election.

Several Americans were in touch with the Russians, though Friday’s indictment does not allege they knew exactly who they were talking to.

Mr. Trump was briefed on the new indictments this week, but has yet to talk about them publicly.

The White House, though, issued a statement stressing that no Americans are accused of wrongdoing in the new indictment.

“Today’s charges include no allegations of knowing involvement by anyone on the campaign and no allegations that the alleged hacking affected the election result. This is consistent with what we have been saying all along,” said White House spokesperson Lindsay Walters.

Hours before the indictments were announced, Mr. Trump said he didn’t have high expectations for the Putin meeting. And he signaled he will warn the Russian president not to meddle in American elections.

But he also again called the ongoing special counsel’s investigation, which produced the indictments, a “witch hunt.”

Instead, he said, it was an effort to “determine how Russia acted to subvert our democracy so that we can ensure precautions are taken this year and in the future to deter and prevent its next attempts.”